[SOLVED] Help! How to know if someone's opened my door?

[Deathray]

I have a friend that has a key to my apartment and have a bad feeling that he might be misusing it by "borrowing" my apartment without my permission.
Now does anyone have some great idea how one can set something up that would indicate someone had opened my front door? Time to be creative :b
And please don't suggest speaking with my friend about it - I'm only interested in an answer to my question (:

EDIT: There is only ONE way out of my apartment and that is the door which I want to rig to tell me if it has been opened.
EDIT: Also, I don't want my friend to know that I know he's been inside. Then once I ask him, he will just say that he wanted to see if I was home sleeping or something like that.

[chris4585]

buy a security camera

[Mazza558]

DNA sample on doorknob.

No doorknob? It's been stolen.

[ssam]

get a small piece of paper and tape it to your door or door frame, in such a way that you can put it in a position, and when the door is opened and closed again it goes to a different position.

[steeleyuk]

Put something behind the door in a marked place, then when it moves you'll know someone has been in.

[bryncoles]

change the locks?

or perhaps you could take hairs unobtrusively over the inner doors or the apartment. wouldnt give you any evidence, but if the hairs were broken then it would confirm if someone had been in there.

[steeleyuk]

A better idea. When you next leave the apartment, connect a piece of string between the door and doorframe. Then when the next person opens the door, it should snap.

[bsharp]

A better idea. When you next leave the apartment, connect a piece of string between the door and doorframe. Then when the next person opens the door, it should snap.

That won't work because he has to open the door to check to see if the string/hair/object placed was broken/moved, thus breaking/moving the string/hair/object.

I think changing the lock would be the best way, although you will never know if they are using it unless they tell you they can't get in.

[bryncoles]

I think changing the lock would be the best way, although you will never know if they are using it unless they tell you they can't get in.

if the locks get changed, then wouldnt the point of whether it was being used become moot, as the answer would become now it isnt (and cant be) used...

[simtaalo]

only give a key to someone you actually trust.

[tom66]

Put a small hair between the door and the frame, but visible so it is exposed slightly outside. If you can see it is dislodged already, the door has been opened. If not, then it has not.

Or, place a newspaper on the floor with a copper coin next to it; when someone steps in the newspaper should be dislodged; if it is closer to the copper coin then...

Tape a piece of paper between the door and the frame inside. If, when you open it, you hear tearing, then the door has not been unlocked yet. If you do not hear tearing, it has been opened before. Try the same thing with: a coin, paper-clip, or string.

Ah, paranoia. Great stuff.

[Mazza558]

Tape a piece of paper between the door and the frame inside. If, when you open it, you hear tearing, then the door has not been unlocked yet. If you do not hear tearing, it has been opened before. Try the same thing with: a coin, paper-clip, or string.

Ah, paranoia. Great stuff.

Once you've taped the door like this, how would you get out again?

[tom66]

Out of the window. Or you could tape one edge, then close the door; the tape *should* stick. Test it to be sure.

[lukjad]

I have a friend that has a key to my apartment and have a bad feeling that he might be misusing it by "borrowing" my apartment without my permission.
Now does anyone have some great idea how one can set something up that would indicate someone had opened my front door? Time to be creative :b
And please don't suggest speaking with my friend about it - I'm only interested in an answer to my question (:
Get a lion. Don't feed it for a week and lock it just behind the door. Tell your friend that you are leaving town and listen too the news. If you hear of a lion running around the city, you know your problem is taken care of, permanently.

On a more serious note, Take a large piece of paper, and tape it firmly to the door and the wall. Test this to see if it will rip when the door is opened. If yes, then tape another one and write something like "Note to self, Remember to oil door handle." If the paper is gone or in a different handwriting, you know. Leave by a window or back door.

You can also, if you want to be tricky, tie some yarn to the door handle. Loop it through something and tape it firmly to the bottom of an open paint can. When the door is open, the paint will spill. BONUS: You can leave by the front door.

The reason I say paint, is that you don't want it to be cleaned up easily. If you have carpet try something else. Also,try putting in a carpet with a bunch of little ketchup things you get from McDonald's under a white rug. After it's in place, right before the door, nail it to the floor. If he steps on it, it will stain the rug and he won't be able to wash it without pulling the nails out. Make sure it is not taller than the bottom of the door, or else you won't be able to open the door. BONUS: You can leave by the front door if you are careful and the door is high enough.

If you want some more tricks, tell me more about what is around your door, and if you have a back door or something. We ninjas are good at this sort of thing. :twisted:

[tom66]

Had another idea. Place a piece of gum or blu-tack over the lock. Said friend will think it is a stupid kid playing around or something, and will likely discard the blu-tack. Then, when you need to get in, remove as normal... if it is there.

[steeleyuk]

That won't work because he has to open the door to check to see if the string/hair/object placed was broken/moved, thus breaking/moving the string/hair/object.

I think changing the lock would be the best way, although you will never know if they are using it unless they tell you they can't get in.

It would work if you were careful opening the door so as not to break the string. Anybody who wouldn't know it was there would just push the door open.

[lukjad]

Unless, of course, they opened it slowly to see if someone was inside.

[hessiess]

Just get the locks changed or demand the frend to give you the key back.

[lukjad]

Just get the locks changed or demand the frend to give you the key back.
Well, that defeats the purpose of having someone to come and unlock your door if you lose your keys.

[RATM_Owns]

Tape a piece of pencil lead at the top of your door, so if it's broken, somebody came in.

[lukjad]

Oooooh! That's a good one. As long as he has a back door that he can get in by, that is.
PS: I love your sig. :lolflag:

[hessiess]

Well, that defeats the purpose of having someone to come and unlock your door if you lose your keys.

Then give it to a different friend that you trust.

[pp.]

Ask the concierge.

[lukjad]

Then give it to a different friend that you trust.
Well, if the friend is innocent, that will just drive a wedge in the friendship for no reason. I think the OP wants to make sure before taking action.

[snova]

I Googled it (as I would appreciate knowing, too) and this thread was the first result. :confused:

Ok, here's an idea... put something behind the door as close as you can while still being able to leave. Remember the position of that object, and when you come back, if the door swings open any furthur than it did before... it's been moved.

Oh, and in case it manages to spark ideas in anybody elses brain, the word "magnet" just flitted into my head (but forgot to bring an idea along).

[Carl Hamlin]

I'm thinking that if the idea is even entering your head that this douchebag might be abusing your trust, you've probably given the key to the wrong person, whether or not he's actually using your apartment. I'd get the key back.

[darrenn]

Setup a webcam with motion.

http://infectedproject.wordpress.com/2007/06/26/set-up-a-webcam-security-system/

[pp.]

(1) Why is it important to you to know if that particular person is using your flat?

(2) You can mount some kind of switch on your door. Connect the switch to your computer running Ubuntu and add an entry to a log file whenever the door is opened or shut. This time, do not give the password to that computer to your friend.

[lukjad]

Well, there are security systems you can buy that have magnetic seals. Maybe that's what you were thinking of? I'm sure there's a way to get one that won't wake up the neighbourhood or summon the police and will let you know someone was there.

[markp1989]

how about just sit at home very quietly, waiting for him to come in?

or, tape a pencil, or pen to the bottom of the door, before you leave, if he has opened the door, the n you will see a curved line on the floor

put baby powder on the doormat, and it will get walked in the house by the person who goes in

[lukjad]

Unless, like, he sees it and erases it. ;)

[snova]

Nor will it work if he has carpet...

[lukjad]

Or expensive flooring.

[solitaire]

Follow the instructions here:
http://tinyurl.com/3bkwkk

Turns PC + Webcam in to a motion detecting security system :D

[offthegrid2]

Just leave things in specific places that you know will have to be moved in order to use the toilet or computer. Take pictures and when you get home compare them to these items to observe if they have been moved.

[master5o1]

In 5th form at high school in electronics I made a crude door alarm system.
This was basically just a reed/magnetic switch attached to the door that turned LEDs on depending on how many times the door was opened.

I think it turned one LED on when opened (reed switch sweep 1). Then it turned another on when closed (sweep 2), then when opened again it sounded t he alarm and turned on the final LED -- presumably when the owner got back.

If I were to create it again I would use four LEDs to show up to 15 open/closes (binary notation). 15 would be 'open' with all LEDs on.
This would tell you how many open/closes there were including your one.
Example:



START: LED: 0000

open 1: LED: 0001
close 1: LED: 0010
open 2: LED: 0011
close 2: LED: 0100
...
open 7: LED: 1101
close 7: LED: 1110
open 8: LED: 1111 << END

[lukjad]

Also, if you think he is there for a few days, or at least long enough to use the toilet, put some sort of dye in the tank. If he flushes, the tank will flush it into the bowl. He probably won't have any handy and you'll be able to see. Also, turn off all the hot water, that'll annoy him!

[myusername]

put something very close to the door. but just close enough so the you can slide thru the door without moving it. if he opens it completely the object will be moved

[jflaker]

I have a friend that has a key to my apartment and have a bad feeling that he might be misusing it by "borrowing" my apartment without my permission.
Now does anyone have some great idea how one can set something up that would indicate someone had opened my front door? Time to be creative :b
And please don't suggest speaking with my friend about it - I'm only interested in an answer to my question (:

I read all the responses and if you want this to stop, just change the locks.

If you want to confront him, then get the video monitor program shown in the thread and email him the vid of him entering your home without permission.

[Deathray]

Thanks for some of the great ideas guys. Also the funny ones like with the lion haha :D.
There is only one way out of my apartment. The front door. There is a window but it is waay to high to jump out of :P. So any other ideas that wont work with these facts I cant use.


put something very close to the door. but just close enough so the you can slide thru the door without moving it. if he opens it completely the object will be moved
An idea like this is probably the best to go with. But it has to be something that looked like an accident so he won't place the object back where it was. Either that or it has to be invisible so he won't notice it.




Well, if the friend is innocent, that will just drive a wedge in the friendship for no reason. I think the OP wants to make sure before taking action.
You hit the nail right on the head.

To the other people suggesting webcam monitoring, I'm only 18 and don't have enough money to have my computer running 24/7 :b


put something very close to the door. but just close enough so the you can slide thru the door without moving it. if he opens it completely the object will be moved
It would be even easier to slide out first with the object and then use my hand to put it behind the door. The question is what?

Also, if you think he is there for a few days, or at least long enough to use the toilet, put some sort of dye in the tank. If he flushes, the tank will flush it into the bowl. He probably won't have any handy and you'll be able to see. Also, turn off all the hot water, that'll annoy him!
I'm home every day so an idea like that won't work.

[Deathray]

In 5th form at high school in electronics I made a crude door alarm system.
This was basically just a reed/magnetic switch attached to the door that turned LEDs on depending on how many times the door was opened.

I think it turned one LED on when opened (reed switch sweep 1). Then it turned another on when closed (sweep 2), then when opened again it sounded t he alarm and turned on the final LED -- presumably when the owner got back.

If I were to create it again I would use four LEDs to show up to 15 open/closes (binary notation). 15 would be 'open' with all LEDs on.
This would tell you how many open/closes there were including your one.
Example:



START: LED: 0000

open 1: LED: 0001
close 1: LED: 0010
open 2: LED: 0011
close 2: LED: 0100
...
open 7: LED: 1101
close 7: LED: 1110
open 8: LED: 1111 << END



An idea like that wont work because then when hes at my place he will ask me what it is then I would have to explain.
Then he will always say that he "just wanted to see if I was home" if the gadget ever told me someone was here. I want the system to be a secret so if I ask him if he came by my house and answers no, I can catch him red handed.

[pp.]

It would be even easier to slide out first with the object and then use my hand to put it behind the door. The question is what?

A glove, cap or shawl; in fact, anything someone is bound to pick up and put into some obviuos place without thinking about it.

Why 'slide out'? When the object is yet to be placed behind the door, you just 'go out'.

You don't happen to have any pets which might be offended by your placing articles in a disorderly manner in your flat and which might dispose of them for you?

[lukjad]

It would be even easier to slide out first with the object and then use my hand to put it behind the door. The question is what?

A small ball or a marble? That would be easy to put there with a finger or two and innocent looking. I am assuming you have hardwood flooring. If that isn't good, try a pencil or pen.

[Deathray]

A small ball or a marble? That would be easy to put there with a finger or two and innocent looking. I am assuming you have hardwood flooring. If that isn't good, try a pencil or pen.
Good idea.


'slide out'? When the object is yet to be placed behind the door, you just 'go out'.
Don't know what I was thinking that was what I meant. And nope, no pets.

I think we can conclude this thread with the solution of simply placing an object in a marked position that either a> won't be seen or b> won't be "thought" to much about. Unless of course you have an idea that's not been said yet and fit's into the situation (:

[lukjad]

Well, there is a way to put a paintball gun so that when someone walks in front of it, it shoots, but I don't think that's what you are looking for. If you want, you could put some sort of liquid outside (like pure vanilla extract). If someone were to walk in with their shoes on, it would come in and you could find it, but I think you would need a dog for that, and I don't think you want to go to that trouble. ;) If I think of something, I'll let you know. In the meantime, try Googling for booby traps, pranks on doors, and home made alarms.

[billgoldberg]

I have a friend that has a key to my apartment and have a bad feeling that he might be misusing it by "borrowing" my apartment without my permission.
Now does anyone have some great idea how one can set something up that would indicate someone had opened my front door? Time to be creative :b
And please don't suggest speaking with my friend about it - I'm only interested in an answer to my question (:

EDIT: There is only ONE way out of my apartment and that is the door which I want to rig to tell me if it has been opened.
EDIT: Also, I don't want my friend to know that I know he's been inside. Then once I ask him, he will just say that he wanted to see if I was home sleeping or something like that.

I didn't read the posts after the OP, so this might have been said.

Buy a webcam that actives when it sees movement. Have it save the images to an external hdd. There are cameras that can send the images to you mobile phone (if the phone is capable) or to other computers over the internet. Or send you an sms message or something.

I don't know if those will work with Ubuntu.

--

There are other, more low-tech and cheaper methods.

1. Trickery

Let your friend know you'll be out of town for a while.

Just stay at home, but make sure nobody can tell you are home from the outside.

If he comes in, you will catch him red handed.

2. Advanced tactics

- The old "strain of hairs" trick.

Plant it them somewhere you are sure it would move if someone was in the house (tv remote, frigde, pc mouse, ...)

- Set your electronic devices to something, so that you would know they have been used.

For example, delete all cookies and clear the cache from your browser before leaving the house.

Check it when you come back, if there are cookies in the browser, you know someone used it.

- Place an object in just before the door.

The object can't move when you open the door, but must be just before it.

Calculate it's distance from the wall.

If someone would enter your house and didn't know it was there it would have moved.

...

[lukjad]

Very nicely put. A good summary, except you forgot the lion.

[Namtabmai]

Buy one of those inflatable sex dolls and leave it on the sofa in your front room.

If next time you see you friend he gives you a weird look and starts s******ing you know he's been in your apartment.

[el_ricardo]

rig your door to trigger the realease of poison gas when it's opened, then if when you come back and there's a dead guy in you're flat, then he's been letting himself in. if you die however, you've got nothing to worry about

sorted :)

[nemonic]

Wow! I have been having this trouble ever since I was old enough to have a lock to my room. My father would just put his shoulder to the door, and I would know it was him that opened my door.
This Ubuntu forum is getting very technical,and this thread is bringing the best brains of the world to bear on it. Yeah right. But occams razor is being brought to bear by some thread posters.
nemonic

[Deathray]

Haha keep on with those type's of ideas. Hilarious :D.

[happysmileman]

It would be even easier to slide out first with the object and then use my hand to put it behind the door. The question is what?

Just a scrap sheet of paper in a ball or something, or a sock, something that will look like you just dropped it or something.

Like make a mistake on your maths homework (or whatever you do, not sure if you'd still be in school at 18 wherever you live), roll sheet into a ball, place behind door, he won't suspect that some badly done calculus is part of a plot to know if he's been there?

Or just something very small and hard to see, something clear?

[Mr. Picklesworth]

Talcum powder? No, really, it could do it ;)

Make sure you clean off your doorknob thoroughly on both the inside and the outside before leaving, (inside especially!) then see to dusting it for fingerprints when you return. Make sure to not get your own prints on the thing because it would take some major expertise to tell the difference between yours and anyone else's. Whether it would work or not comes down to what kind of doorknob you have.

[tuxsheadache]

Bear trap, works every time.

[Saint Angeles]

hold a glass of water (not too much though) and when you are closing your door, slip the glass onto the floor behind your door. do this when you have like, 6 inches open.

when you come back to check on it, open your door slowly in case the water glass is still there. you should be able to pick it up without spilling anything.

if the glass has been spilled, well... you get the idea.

or make a pretty design on your doorknob using honey or something sticky like that... if the design has been disturbed, somebody has been touching your knob.

they have videocameras, like sony ones, that can be motion activated. people use these as nanny-cams to ensure their babysitters arent beating their children. you could use one of those fairly easily.

is this your front door you are talking about? because you might be able to ask a neighbor to keep an eye on your door and tell you if he sees anybody entering.

[Mr. Picklesworth]

If your apartment has more than one lock, do not lock the top one and remember that. Alternate the pattern from time to time. It may take a while, but eventually you could find both locks locked even though only one is meant to be.

[tuxsheadache]

Set up a motion detector? There are some devices in the market that take a picture when they send motion and email it to you. Slightly obsessive, but I think it can be done with normal webcams if you research into it.

[Mardoct909]

Kill him. Then you can be sure he isn't entering your apartment.

Or you could just put a note up opposite the door that says: "I know you've been here. I'll give you a second chance, though. Let's just pretend this never happened." It'll scare him into stopping it if he is doing it, and if not you won't notice the difference.

[tuxsheadache]

Leave your computer playing a "shock website" involving some random p0rn that should never have been seen. If he looks terrified when you come home, or refuses to talk to you, yep, he has seen it.

[Saint Angeles]

Leave your computer playing a "shock website" involving some random p0rn that should never have been seen. If he looks terrified when you come home, or refuses to talk to you, yep, he has seen it.
we have a winner!



make some kind of script that displays the worst, hardcore, _____iality, ____phile porn that changes every 20 seconds and plays some gross horrible noises while doing so. and make it so you need a sudo password to turn it off.

also, leave out some disgusting sex toys and spread some gross food items all over it so they look... well... used.

also, hide some rotting fish in the apartment and maybe some feces so that nobody would ever WANT to go into your room.

if you think he's using your bed, put a bunch of thumbtacks inside the sheet poking up so he gets very mutilated if he lays down.

[tuxsheadache]

What can I say? I know how to shock people with bad images from the Internet.

[Grant A.]

we have a winner!



make some kind of script that displays the worst, hardcore, _____iality, ____phile porn that changes every 20 seconds and plays some gross horrible noises while doing so. and make it so you need a sudo password to turn it off.

also, leave out some disgusting sex toys and spread some gross food items all over it so they look... well... used.

also, hide some rotting fish in the apartment and maybe some feces so that nobody would ever WANT to go into your room.

replace sex with 'chew' and it sounds like you will need some K-9 Jelly. ;)

[barbedsaber]

I assume you have one of these (http://www.china-handles.com/productsimages/DoorhandleLeverhandle_10413.jpg) types of handles.
lower it by about 5 millimeters, so that when it is opened, it will return to horizontal.
Idea from episode 8 of deathnote.

[TwiceOver]

Pretty easy actually, just wedge a toothpick in the hinge side of the door toward the bottom.

[pp.]

Build a trapdoor just behind the door to your flat. Do not come home drunk, though.

[lukjad]

Hahahahahaha!

[markp1989]

if the door handel is metal, connect it up to the mains, if he does come to your home , it will give him a nice shock :P

[lukjad]

And if you get home first, all your problems will be over.

[whitegourd]

From the outside of the door cut out a small strip of clear tape and on that strip cut it half way across and tape one side to the door and the other to the door frame.

That way when the door is open, it'll easily split the strip w/o any noise and won't be easily detected.

That's how I caught my roommate opening my desk drawers when I wasn't home.

[s.fox]

Leave a ping pong ball sitting in a fixed location just behind the door. If your friend comes in he will move the ball and probably won't notice or hear it. When you come home carefully open the door and see if the ball has moved using a mirror.

Hope this helps.

P.S. Alternatively leave a video capture device recording running when you go out.

[snova]

The idea of leaving something just behind the door has come up several times. I think that's one of the best ones- it's simple and effective.

The addition of a mirror was a nice improvement that I didn't think of, that eliminates the risk of moving it yourself.

[Deathray]

From the outside of the door cut out a small strip of clear tape and on that strip cut it half way across and tape one side to the door and the other to the door frame.

That way when the door is open, it'll easily split the strip w/o any noise and won't be easily detected.

That's how I caught my roommate opening my desk drawers when I wasn't home.

I think we have a winner here. What's also great about it is no need to be careful. I simply close my door and tape the tape to the door and door frame and leave. Simple, but effective.

[NE Key]

As you leave and close the door place a matchstick or similar inconspicuous object in between the outside of the door and the door frame on the hinge side.

When the door is opened it will fall out.

You will be able to check, before you open the door yourself, if the door has been opened while you were away.

[dantakeoff]

heres an idea. leave a message for your friend ,loud and clear, like a huge poster or piece of paper saying : (name of friend) if you have any respect for my privacy then please dont come here without asking or at least telling me first...

[Nano Geek]

I think that, as long as you have the money, using a security camera would be the best choice. If your friend has been going into your apartment without your permission, then he will probably deny it when you ask him about it. Having video proof would be helpful.

As they say, the camera never lies.

[Nano Geek]

As you leave and close the door place a matchstick or similar inconspicuous object in between the outside of the door and the door frame on the hinge side.

When the door is opened it will fall out.

You will be able to check, before you open the door yourself, if the door has been opened while you were away.Or rig the matchstick to light as it falls. If your friend has no hair when you come home, you know he has been in your apartment. :)

[Thelasko]

The oldest and most famous method I ever heard of is to put a piece of hair across the door and the frame. Others have mentioned it, and though I have never tried it, in the movies it works like this:


Get a piece of hair.
Get it damp (saliva works fine) so it will stick.
Place it across the gap between the door and the frame on the outside of the door.

The idea is, that the hair is small and not noticeable. If it is noticed, it is reasonable that it landed there by coincidence.

This might make some good material for the Mythbusters to prove.

[BobLand]

If you really care then change the locks and don't give out your keys. Are you afraid of hurting someone's feelings? You are implying that you are hurting your own feelings by posting this.

bobland

[joninkrakow]

As you leave and close the door place a matchstick or similar inconspicuous object in between the outside of the door and the door frame on the hinge side.

When the door is opened it will fall out.

You will be able to check, before you open the door yourself, if the door has been opened while you were away.

Definitely the matchstick (or toothpick that someone else mentioned) is the trick. Put it on the hinge side, and you will know, so long as you remember to check before you open the door. This is as simple as it gets.... and quite foolproof.

-Jon

[Deathray]

Definitely the matchstick (or toothpick that someone else mentioned) is the trick. Put it on the hinge side, and you will know, so long as you remember to check before you open the door. This is as simple as it gets.... and quite foolproof.

-Jon
Case closed. Definitely the best.
I'm going to go ahead and mark this thread as solved.
Thanks for the help guys :)

[Dr Small]

I've built traps for my keyboard tray before, to see if anyone had been using my computer while I was gone. To do this, I set up a stack of coins in the back of the tray with a bent nickle on top of this (I shot the nickle with a .22 bullet) and placed a small plastic figurine on top. When a person opened the keyboard tray, the figurine wobbled and fell.

But for your case, with a door, I would try the same concept, but have a thin wedge stuck in the top of the door with something inconspicuous on top of it. Wedge it in about half way across the door so you can get out, and test it several times to verify that it will work.

When the person opens the door, the wedge will either be pushed out far enough to fall, or will slightly move enough that when he closes the door it will slip out and fall. That's just my idea, but I'm sure I would come up with some other things to try.

[Maheriano]

How is this so complicated? Just glue a magnet to the bottom of your door and leave a coin on the floor right behind it. He opens the door, magnet scoops up the coin and he has no idea anything happened. When you get home, open the door really fast so it doesn't catch the coin in case he wasn't in.

[TorqueyPete]

only give a key to someone you actually trust.

Amen to that!
A friend is just such a person. ;)

[lukjad]

@TorqueyPete Trust and friendship can be broken.

[Lostincyberspace]

Make a lever using something like a long ruler and a pencil. Place a magnet at one end closest to the wall and tape another magnet close enough to it that when they step on the other end it will catch the magnet. Cover the long end with a mat or towel.
My opinion:
Kind of hard to make unobtrusive.

Alternatively, just place a bunch of pencils in a line or two on a mat, so when they step on it they break the pencils. You will probably be only able to make 2 lines of pencils.
My opinion:
Easy to set up kind of unobtrusive.

Another alternative: Get a bunch of pencil leads for mechanical pencils and lay them in a line far enough that the door will not hit them, but close enough that they will step on them.
My opinion:
My favorite, of them all easy to do pretty unobtrusive.

[Daggo]

Ever see the movie "Home Alone"? You can get a lot of sinister ideas from how the kid booby traps his house.

serious answer= I like the tape idea. make is small, make it subtle.

[Dr Small]

How is this so complicated? Just glue a magnet to the bottom of your door and leave a coin on the floor right behind it. He opens the door, magnet scoops up the coin and he has no idea anything happened. When you get home, open the door really fast so it doesn't catch the coin in case he wasn't in.
Coins are not metal, I don't think. A magnet won't pick them up, unless I am mistaken. I could be wrong though, as I have never tried...

[Lostincyberspace]

Coins are not metal, I don't think. A magnet won't pick them up, unless I am mistaken. I could be wrong though, as I have never tried...
It depends on where you are from, I think in Cuba the coins might not be metal but almost if not every where else in the world they are. I believe quarters a magnetic. But you could use a washer too same effect.

Another variation on this is to tie a string to magnet and place it on the door and attach the other end to the frame or something. If it is not in the same some one you get back then someone has gone in.


Hey doing this really fun any more challenges?

[Private_Ops]

It depends on where you are from, I think in Cuba the coins might not be metal but almost if not every where else in the world they are. I believe quarters a magnetic. But you could use a washer too same effect.

Another variation on this is to tie a string to magnet and place it on the door and attach the other end to the frame or something. If it is not in the same some one you get back then someone has gone in.


Hey doing this really fun any more challenges?

Quarters are not magnetic. If I'm not mistaken they're made out of copper and silver... maybe some Zinc... not really sure.

Washers would be a better options since they're made of steel (usually).

[Maheriano]

Canadian quarters, dimes and some nickels are magnetic. I used to carry a magnet around in my pocket just so I could easily get all the coins out without having to scoop my hand around the bills. That way I didn't come up with any stupid pennies either.

Anyway, the actual best way to do it is to buy a $10 webcam, hook it up to your computer and just run recording software like ZoneMinder. In total it costs you $10 and it's the easiest.

[forrestcupp]

Just the fact that you gave the guy a key implies that you are allowing him to enter your apartment while you are gone. Why else would you give him a key? So since you implied that he is allowed to enter your apartment while you're gone by giving him a key, he's not doing anything wrong if he enters your apartment while you're gone. So there's no reason to even try to "catch him red handed".


Coins are not metal, I don't think. A magnet won't pick them up, unless I am mistaken. I could be wrong though, as I have never tried...
Coins are metal; it's just that some of them aren't made out of the metal called iron that is magnetic.

[Thelasko]

Coins are metal; it's just that some of them aren't made out of the metal called iron that is magnetic.
It works if the material is ferromagnetic (http://en.wikipedia.org/wiki/Ferromagnetic). There are only three elements that are ferromagnetic at room temperature (http://www.tf.uni-kiel.de/matwis/amat/elmat_en/kap_4/advanced/t4_1_3.html), they are Iron, Cobalt and Nickel.

[markp1989]

Just the fact that you gave the guy a key implies that you are allowing him to enter your apartment while you are gone. Why else would you give him a key? So since you implied that he is allowed to enter your apartment while you're gone by giving him a key, he's not doing anything wrong if he enters your apartment while you're gone. So there's no reason to even try to "catch him red handed".


Coins are metal; it's just that some of them aren't made out of the metal called iron that is magnetic.

He has given him a key for emergances , not to use his flat when he is not there

[pp.]

Glue the door shut and wait for him to comment on it.

[issih]

Simplest solution is probably to leave the house, and as you leave wedge something into the door frame (e.g. a twig or something else that won't look totally out of place) then when you return if the wedged item is missing the door has probably been opened. Not foolproof, the postman could have just pulled the wedge out, but at least its easy :)

[DonaldJ]

I've heard that this is where you can set up an electronic counter, with a secret contact that fires the counter every time the door-latch inserts into its slot.. or add a plastic flap at the top of the door-frame, hiding a set of contacts that make whenever the door has been opened... Use fine plastic-coated circuit-board bridge-wire, and hide it in a corner under caulking...

You can make a pressure-sensitive floor-mat switch that fires a camera, or a motion sensor that triggers a video cam... Cam is positioned to take a complex image reflected by several strategically placed mirrors... Cam is hidden in a dark shadow, or in a tube, far enough away to make the click inaudible to the criminal... Maybe something in the room could be set to drown out the sound of the camera, like a fan, with long flappy strings attached to the blade-cage...

I don't know how you could make an electronic camera fire from an external switch..? That's the tough part...

Make the pressure sensitive mat-switch from an old keyboard keypad...
Remove the keys, and somehow glue the rubber pistons to a firm material..?

Maybe set a video cam to take a single shot every couple minutes...

Probably the simplest MO is a motion-detector set to a video camera and VHS or DVD recorder, hidden in a locked secret place, that no one could get at, like in the trunk of a vehicle... All depends where you run the wires to...

I had this problem with a new dive apartment I moved into in a pinch... The old hag was forever going into my rented apt when I was out, and was snooping through all my stuff like it was hers.. like she had nothing else to do with her life... My solution was highly illegal, but it got the message across... I taped my empty S&W chief's special to a chair back, aimed at the door, with a string attached to the door-knob... When I returned, the pistol hammer was down... No one snooped in my apt for the remainder of the duration of my stay in that shid-hole place... If she had have called the cops about the gun on the chair, I would have lost my snub-38... I bet one that gave her nightmares...

[thisllub]

Check the sheets to see if the bed has been "used"

[tom66]

Wire up a switch which is closed when the door is closed and open when it isn't, then plug it into a decade counter. Wire a 9V battery in to power it for a day or so. This small circuit will count the number of times someone has opened your door up to 10 times. If you want more precision, wire in another decade counter to the /10 input on the chip, and keep adding these for each power of 10.

[DonaldJ]

Purchase half a dozen door-locks.. and install different ones for different times... It's just a couple philip's screws, and it's done...

Test the quality of the lock by trying to break-in for twenty minutes...
If you can easily break-in, any one can...

Those push-knob door-locks, and those little turny thing in the middle of the inside knob door-locks are all BS at best.. You might as well just set a rock against the door.. A little wedge of wood would be more secure than those locks... I can open any locked one of those silly door locks in 3-seconds.. I learned it frum der teevee...

The only secure door lock is a 1-inch cold rolled square rod slider with an Ace lock.. that slides into a 3/8 steel plate door-frame.. and wicked thick hinges also bolted to the steel door frame... Most doors can be bashed-in by one good hit with a sledge hammer to the lock, or a couple hits to the hinges.. or simply slam the door with a pickup's rear bumper...
One place in the city got slammed by a pickup, and it took-out the whole aluminum and glass store-front...

When I'm securing a commercial-door to be hammer and crowbar proof, I build-in a 3/8" by 3" steel strap door frame, held to the wall by 15" by 4" 3/8 strapping, bolted through the wall with blind bolts, doubled nutted, and weld thick hinges with half-inch pins to the frame, and door...

[t0p]

One of my pet peeves: people who won't read ports properly. The OP wants to know if his neighbour has been using his place. If doesn't want to know how to secure his apartment; he doesn't need to hear how he shouldn't give keys to people he doesn't trust. But some people give him this crap regardless. *sigh*

Anyway. I assume the OP has internet access and a computer. Get a webcam and position it so it covers the door. Set it up so it sends its output to a remote server. Now you can set it to work when you go out, and you study the footage at your leisure. Job done.

[diablo75]

Butter the floor (http://video.google.com/videoplay?docid=1544195365224370576&ei=zHKESZ2qGouQ-wG7zbj8Cg&q=butter+roommate+floor&hl=en) behind the door before you leave.

[jakupl]

Put lava on the floor. Then he will burn himself if he enters....
Or
Constantly play opera music, so that if he enters, his head will explode.

[TripleJayD]

Put scotch tape on the floor with the sticky stuff pointing up. Check your own shoes before confronting him.

[price13]

Hi guys, first post, sorry to bring up such a old thread but i have a simular thing.

long story short, im giving my girlfriend a locket after some trust issues. I am seeing if i can trust her not to open it for like 2 months and keep it safe. BUT, I can not think of any way to make it so i can tell if it has been opened. Basically, i want something that would do something the first time its opened, but would never be done again and cant be re-created easily.

My ideas so far would be a chemical reaction of some kind or using silly-putty somehow. Or after reading this thread, maybe a hair somehow? I don't know if/how either of these would work though.

the l;ocket is in the shape of a heart and is decent size, not a tiny tiny one.

Any ideas/ suggestion would be helpful ! :)

PS: could a mod plz remove the solved tag on the title so people dont just look over this :)

[mmsmc]

put a peice of duck tape on the door crack where your friend cant see it, the if it is ripped youll know

[Timmer1240]

put a candy dish in there of some kind of candy they like count the pieces b4 you leave when you return count them to see if some are gone problem solved!Or have so many cans of some pop that they like in the fridge say 12 cans see if one ore two are drank put the tv on some boring channel like pbs then when you get home turn it on see if its been changed!just note how everything is and look for anything thats been changed when you get back.

[Timmer1240]

way better ideas than taping the door or some such sillyness when you open it yourself it will be brocken anyways from you!

[Perfect Storm]

Necromancing. Thread closed.